1. Field of Invention
The invention relates to a shredder. In particular, the invention relates to an anti-jam device for the shredder. In the AUTO mode, the passage width provided by the anti-jam device is exactly the maximum thickness of paper that can be fed each time. In the REV mode, the anti-jam device provides a larger passage width for the paper to be backed out easily.
2. Related Art
To prevent such documents as legal files, receipts, invoices, credit card numbers, research reports, or personal financial information (e.g., credit card and phone bills) from being released, it is common to destroy them using a shredder. Therefore, the shredder has become an indispensable device for both business and home applications.
The action principle of a shredder for shredding paper is to dispose several cutting blades on two rotary shafts with spacers in between. A motor and a gearbox are employed to drive the two parallel rotary shafts that rotate in opposite directions. They provide a shearing force on passing paper to cut it into small stripes.
The motor load and the strength of the cutting blades and rotary shafts limit the sheet capacity allowed by the shredder each time. That is, when many paper sheets need to be destroyed, the user has to limit the amount of paper each time. Otherwise, there may be paper jam occurring to the rotary shafts. Therefore, in order not for the user to put in too much paper at a time, it is necessary to provide an anti-jam device that automatically restricts the number of sheets.